STEM and the Art of Floating Floating means remaining as motionless as possible in a position—on your back, face up— so you can still breathe using as little energy as possible. Target audience: Many Scouts think they can float by sculling the water with their hands and keeping their feet on or near the surface of the water. Others are convinced they can’t float and have given up a long time ago. Fact is, anyone can float if he understands the fluid dynamics principles involved. It’s all about density! Let’s begin with Archimedes’ principle—an immutable law of physics fundamental to fluid mechanics: The upward buoyant force exerted in an object immersed in a fluid (e.g., water), is equal to the weight of the fluid (water) displaced by the object. Rocks sink because they are denser than water. A buoy floats because it is less dense than water. Your body is somewhere in the middle. Our boats and kayaks are made of materials denser than water, but they float because we shape them to include air in the displacement. We can do the same thing with our bodies, which are just a bit denser than water. Filling our lungs with air shifts us to a bit less dense than water and we can float. The human body, on average, weighs about 77 lbs. per Cf, so the average person will naturally sink; not float…Unless we (1) make our bodies larger and (2) do this by adding air. When we do this sufficiently, we (a) displace more water and thus (b) approach the 62 lbs. per Cf. (the weight of water) that we need to stay afloat. Where do we hold our air? In our blood and—mostly—in our lungs. So, if we spread our arms upward and outward—
cross-­‐like—in the water we expand our body size and add more air at the same time. We, in effect, become the same as that steel ship that floats because the water it displaces weights more than the ship’s total weight. So, the next time you want to float, here’s what to do: From a vertical position in the water, roll your head back so you’re looking at the sky or ceiling, spread your arms wide, keep the palms of your hands facing up, and take (and hold) a huge breath. Maybe just your mouth and nose will be above the water’s surface, but you’re actually floating. If your feet sink, let them (they won’t pull you down). When the breath of air you took in becomes uncomfortable and you want to change air, rapidly blow all the air from your lungs and instantly suck in a fresh breath of new air—and do nothing else. You’ll continue to float for as long as you like. Trust Archimedes—he’s been right for nearly 2,300 years—trust the water, and trust yourself! 1 Saddle Road
Cedar Knolls, NJ 07927
Phone: 973-765-9322
Fax: 973-267-3406
www.programs.ppbsa.org/stem
www.beAscout.org